My car wont rev past 3k RPM with throttle and in gear but in neutral revs and idles fine

I was driving to work yesterday and the car was running great no problems and then after I drove 30 miles it started to a little bit of rough idle and as I got closer to my work it wouldnt rev past 3k rpm and everytime I tried it lost power and wanted to shut off but gradual gas it would still keep going then I kept losing speed so I pulled over and when I did back fired really loud and I was stopped at this point and idled fine and I thought to move more off the road to move it and I was able to drive it 10 feet without any of the previous symptoms I have no cel codes and have reset the comp to see if I get any codes but I dont

ive replaced the distributer with 1 from autozone for 350 bucks lifetime warranty I have brand news wires ngk v power plugs and I also changed coolant temp sensor and I recently change the clutch cause the pilot bearing was making noise and there were two grounds in the back of the transmisson one pretty thick and its black and yellow other very thin and all black and I put them on that same number 10 bolt thinking there both grounds idk if that could be a problem it has a new pcv valve and I cleaned the throttle body and iac valve ive sprayed the vac lines with starter fluid didnt change in idle speed or anything, the fuel pressure regulator is very old but could that cause my problem I need to check timing marks and make sure that the on and right but I pulled the disty cap off and all of the pins are being hit by the spark from the rotor the plugs apeared to be a very very light brown